fn main() {
  let _x =5;
  // _x =6; cannot assign twice to immutable variable
  let mut _y=5; //can not mut same x
  _y =6;
  static X1:i32 =5;
  static mut X2:i32 =5;
  const X:i32 =6;
  //const mut X =6; //cannot be mutable
  unsafe{
    X2 =12; //need unsafe to modify static varables
  }
}
